The present invention relates to a method and apparatus for atomizing atomizable coating material, such as a powdered coating material, and relates particularly to such a method and apparatus in which atomizable material is expelled from an atomizable material transmission channel through a funnel-shaped orifice without need for insertion of an additional body into the flow of material to shape the cloud of atomizable material by deflecting it.
Devices of this type are known from West German Provisional Patent (Auslegeschrift) No. 14 27 642 and West German Unexamined Application for Patent (Offenlegungsschrift) No. 17 77 284. In them, a swirl chamber is provided between the atomizable material channel and the funnel-shaped orifice to the exterior. A gas channel for injecting a gas, normally air, into the powdered atomizable material, for causing eddies in the powder, discharges into the swirl chamber near to but not directly at the entrance of the orifice. The actual atomization in such known arrangements takes place further downstream and is due to the turbulence produced at a sharp mouth edge provided in the orifice. In this way, however, only a very narrow jet of atomized material can be produced. If, as in most cases, a wider, more diffuse cloud of powdered atomizable material, is needed to be expelled from the orifice, inserts must be provided in the orifice, as shown in FIGS. 3 to 5 of the above-mentioned German Application No. 17 77 284, to deflect the atomizable material into a cloud of the desired shape. Atomizing atomizable material such as a powder by the use of baffle plates in the flow of material is known from West German Unexamined Application (Offenlegungsschrift) No. 15 77 760 and West German Pat. No. 17 52 027.
West German Pat. No. 20 30 388 discloses charging atomizable material electrostatically so that it is attracted by the object which is to be coated and thus adheres better to it, with less of the atomizable material being lost.